31 



In the year 1860, which, by the way, is the most important 

 epoch in the history of this subject, the matter was taken up in 

 good earnest by the Germans, principally Kuchenmeister, 

 Virchow, Leuckart, and Zenker. I will not trouble you by 

 stopping to relate sepai-ately tlieir individual labours, but will 

 give at once a brief summary of their united discoveries. They 

 showed that the Muscle Trichina was an immature form of the 

 worm. When swallowed, the cyst soon dissolves in the stomach 

 and the worm is set free. It then gradually straightens itself 

 out, rapidly grows, and by the second day is sexually mature. 

 According to Althaus, the numbers of males and females are at 

 first about equal; the males however, rapidly diminish, and 

 after a period of from ten to sixteen days, females only are 

 met with. The males are from 1 mm. to 1| mm. in length, 

 the females about double. The young soon appear as minute 

 coiled up threads enclosed in the ova within the bodies of the 

 females. They escape from the shells, and after the sixth 

 day pass out aUve at the genital aperture. On exit, they are 

 small, transparent, and devoid of special organs, and of about 

 l-20th mm. in length. Each mother contains from 5,000 to 

 15,000 eggs. Very soon after birth the young ones commence 

 their travels, and in about 1 days after their parents have been 

 swallowed, will have arrived in the muscles. They infest all the 

 striped muscles, especially those nearest to the abdomen and the 

 laryngeal muscles ; the heart very rarely indeed. After arriving 

 in the muscle, they undergo further growth and development for 

 14 days, Avhen they become coiled up and assume the size and 

 form of the muscle Trichina. They now have an intestinal tube, 

 which extends from end to end, and the males and females ai-e 

 distinguishalile. From the third to the fifth week they become 

 gi-adually enclosed in the cyst. According to Yogel, the deposit of 

 chalk begins at the fifth month, commencing at the ends of the 

 cysts. In this condition, Bi'istowe says, they remain alive for 

 many years, even after the death and decomposition of their hosts. 

 The parent worms have been found in the intestine as late as seven 

 or eight weeks after being swallowed, but usually disappear earlier. 

 As females have been found at this late period full of ova, it is pro- 

 bable that they bear several broods. The exact method by 

 which they escape from the intestine is not altogether understood. 

 It was at one time supposed that they worked their way into the 



